How much to set aside each month
The quarterly scare is almost never about paying a lot. It is about having set nothing aside. And doing it properly needs two rules, not a spreadsheet.
Rule one: the VAT is not yours
When you invoice €1,000 plus €210 of VAT, you collected €1,210 but you earned €1,000. Those €210 are the tax office's money passing through your account.
Separate it the day it arrives. If you force yourself to look at a balance that already excludes VAT, you stop spending it without noticing.
You can offset the VAT you paid on deductible expenses, so what you actually owe is usually less. Setting aside too much never hurts.
Rule two: 20% of profit
The quarterly income tax instalment under direct assessment is 20% of the year's accumulated net profit, minus what you paid in earlier quarters and minus the withholdings applied to you.
If you invoice companies, much of it is already withheld at 15%, so the form comes out lower. If you invoice individuals there is no withholding and the hit lands in full.
What gets forgotten and hurts
The self-employed social security contribution is a deductible expense, not a separate tax. It belongs on the expense side.
A mixed expense like a phone or a car is rarely 100% deductible. Record the percentage you apply and be able to justify it.
Negative results from a bad quarter offset later ones. If you do not carry them forward, you overpay.
One month as an example
You invoice a company 3,000 € plus 630 € VAT, and it withholds 15% (450 €). You receive 3,180 €. Your deductible expenses for the month total 600 € plus 126 € VAT, and the self-employed contribution is 294 €.
VAT to set aside: 630 € collected minus 126 € paid, 504 €. Income tax to set aside: 20% of profit (3,000 € minus 600 € minus 294 €, that is 2,106 €) comes to 421 €, and 450 € has already been withheld. This month the modelo 130 is zero and you are 29 € ahead.
If the same client were a private individual there would be no withholding and you would have to set the 421 € aside yourself. The rule does not change; who advances the money does.
One flat percentage so you never have to think
If you prefer a single figure, set aside from every payment: all the VAT, plus 15% to 20% of the base if you invoice companies, or 25% to 30% if you invoice individuals.
It is more than you will pay, because it ignores expenses. That cushion is what makes the 20th painless. Whatever is left at the end of the quarter is savings, not a mistake.
Where to keep it
A second account in your own name, no card, with an automatic transfer on the day you get paid. It does not need to be a business account; it only needs to be out of sight when you spend.
On 20 April, July and October, and on 30 January, the money leaves from there and nowhere else.
Frequently asked questions
What percentage of each invoice should a Spanish freelancer save?
All of the invoice's VAT plus, for income tax, 15% to 20% of the base when the client withholds tax, and 25% to 30% when the client is an individual and nothing is withheld. It is a conservative rule: what is left over is yours.
If my clients withhold 15%, do I still file the modelo 130?
You are exempt only if at least 70% of last year's income carried withholding. Below that threshold you file it even when the result is zero or negative.
When is the quarterly payment due?
From 1 to 20 April, July and October for the first three quarters, and from 1 to 30 January for the fourth. If you pay by direct debit, the window closes five days earlier.
Is the self-employed contribution deducted before the 20%?
Yes. It is a deductible expense, so it lowers the profit on which the instalment is computed.